1. Field of the Invention
The present invention relates to an Ethernet passive optical network (EPON), and more particularly, to a method for managing a service bandwidth by a customer port and an EPON system using the same for controlling a bandwidth dynamically according to a service provided through the EPON system.
2. Description of the Related Art
As next generation access network technology for providing a communication and broadcasting integrated service and a fiber to the home (FTTH), passive optical network (PON) technology has been receiving an attention. The PON technology has an advantage of a broadband service that can accommodate voice, data and broadcasting at the same time in an access network which has been suffered for the bottle neck problem. It is expected that the PON technology will contribute for constructing and popularizing a digital home. Especially, an Ethernet based PON (EPON) occupies 95% of Internet traffic. Hereinafter, standard progress, technical features, economic benefits of the EPON will be described.
The standardization of the EPON has been in progress by IEEE 802 LAN/MAN standard committee. As recently decided access network technology, three types of wired lines such as a point-to-point copper wire, a point-to-point optical cable and a point-to-multipoint optical cable have been used. The EPON provide 1 G of a transmit rate, 1:16 of a divergence rate, and 10/20 Km of a target transmission distance.
The EPON has a point-to-multipoint network structure and uses a passive optical distribution unit. The EPON does not require active elements such as a reproducing device and an amplifying device, minimizes the use of an optical cable and reduces optical ports in a center office. That is, the EPON is a passive optical access network allowing easy and economic management. The EPON may be an affordable plan for building a FTTH based or a fiber to the business (FTTB) based access network in the case of a new apartment where an optical cable is installed.
Hereinafter, a conventional EPON system will be described with reference to an accompanying drawing.
FIG. 1 is a block diagram of a conventional EPON system.
Referring to FIG. 1, the EPON system according to the related art includes an optical line terminal (OLT) 10 for accessing service providers and networks used by the service providers 11 to 1N, and optical network units ONU 31 to 3N for accessing a user. The ONU is similar to an optical network terminal (ONT) 40 which a similar structure of a typical MODEM. However, the ONT 40 is distinguished from the ONU because the ONT 40 provides a connecting means to user to allow a user to directly access the ONT. Also, the EPON system includes an optical distribution network (ODN) 20 for distributing a physical link to a plurality of links in order to enable a plurality of ONUs/ONTs to connect a signal physical link provided by the ONT.
As shown in FIG. 1, the EPON system provides a logical link identifier (LLID) for logically discriminating the ONU from the ONT. The ONUs 31 to 3N and the ONT 40 provide a media access control address (MAC) in order to access the OLT 10. The OLT 10 provides a means for identifying the ONUs 31 to 3N and ONT 40 by mapping the MAC addresses of the ONUs 31 to 3N and the ONT 40 to the LLID, and provides the MAC addresses to the ONUs 31 to 3N and the ONT 40. The OLT 10 provides a means for physically detecting equipment used by a service provider or other network equipment used by the service provider to access the OLT 10. Also, the ONU 31 to 3N and the ONT 40 provides a means for physically recognizing equipment used by a customer.
As shown in FIG. 1, a service provider provides a service through the EPON system and also provides a means for recognizing a type and a feature of a provided service. That is, the service provider recognizes the type and the feature of the service requested by a service application terminal and provides corresponding services according to the recognizing result. The EPON system and the service provider may set rules for services and may control or manage the service passing through the EPON system according to the rules.
The EPON provides a limited bandwidth for delivering a service. The limited bandwidth of the EPON is not sufficient to deliver recently introduced various services. Therefore, it is required to control the bandwidth for using a service or receiving a service based on a contract made by the EPON system, a service provider and a customer.
The conventional EPON treats a service itself more importantly than a customer connected to an ONU or an ONT. That is, in a view of quality of service (QoS), a service is classified into a plurality of levels, and the bandwidth and transmission delay are controlled according to the level of the service. Recently, various types of services were introduced and become popular among people. Therefore, it is recognized that the bandwidth provided from the EPON is very limited to accommodate such various services. Due to the limited bandwidth of the EPON, it requires a means for controlling a service bandwidth not only according to QoS but also according to a service policy.
In order to satisfy such a requirement, a method of assigning a priority to a service in a PON customer terminal was introduced in Korea Patent Publication No. 2005-0061263.
In the conventional method, a method for providing a service to a customer terminal having a priority and a PON system using the same are introduced. In more detail, a priority is assigned to customer terminals in a PON, and the PON system receives a reservation request message from a customer terminal to request a bandwidth allocation for data transmission. The received reservation request messages are stored in corresponding queues according to the priority of customer terminal that transmit the reservation request messages. Then, the PON system provides requested services to the customer terminals in an order from the reservation request messages stored in the queue having the highest priority to the reservation request messages stored in the queue having lower priority. As described above, a discriminated service can be provided by assigning priorities to predetermined customer terminals.
Also, a method of identifying a customer using an IP address was introduced in Korea Patent Publication No. 2005-0032678. The method includes the steps of: assigning bandwidths to ports of a plurality of customer terminals connected to a service provider terminal and assigning customer levels; allocating a bandwidth by a customer port of a customer terminal based on the bandwidth information; allocating an ID address to the customer port of the customer terminal according to the customer level based on the customer level information; and differently supporting QoS according to the customer level for data transmission between the service provider terminal and the customer terminal using the bandwidth and the IP address.
However, the first conventional method has a problem that a discriminated bandwidth cannot be provided according to the service type because the customer is discriminated by a unit of ONU/ONT. The second conventional method must assign an IP address to a customer port for discrimination. Therefore, the second conventional method must perform annoying processes for mapping the customer port and the IP address, checking the mapped information according to the customer port, and checking the service of the checked customer port whenever the IP address is dynamically allocated through DHCP.